Material for imparting thixotropy and pasty resin composition

ABSTRACT

Surface-treated calcium carbonate characterized by giving, upon analysis by the method of mercury penetration, a void diameter distribution curve which has a peak for the most probable void diameter at smaller than 0.03 μm and has a most probable void volume of 0.05 to 0.5 cm 3 /g; and a pasty resin composition containing the surface-treated calcium carbonate. The calcium carbonate preferably comprises one obtained by surface-treating calcium carbonate having a BET specific surface area of 10 to 100 m 2 /g with an unsaturated fatty acid (A) and a saturated fatty acid (B).

TECHNICAL FIELD

The present invention relates to a material for imparting thixotropycomprised of surface-treated calcium carbonate and more specifically toa material for imparting thixotropy useful for addition to variouspolymer materials such as inks, paints, sealants, polyvinyl chloridesols (PVC sols) and acrylic sols. The present invention also relates toa paste resin composition containing the surface-treated calciumcarbonate and more specifically to a paste resin composition useful as apolyurethane sealant, modified silicone sealant, silicone sealant,polysulfide sealant, polyvinyl chloride sol, acrylic sol or the like.

BACKGROUND ART

Inks, paints, sealants, PVC sols, acrylic sols and the like aregenerally prepared in the form of a sol which is convenient for practiceof painting, coating, applying, mixing or the like operation. In caseswhere the required physical properties or qualities of a cured endproduct hinder high loading of a filler in the sol, fumed silica or thelike filler has been conventionally used which, even in a small amount,can impart an increased viscosity to the sol.

However, because fumed silica is generally high in cost, a need hasarisen for a substitute material for imparting thixotropy which is lessexpensive but yet can impart a high degree of viscosity. Calciumcarbonate has been used in a wide variety of fields, for example, as afiller for plastics, rubbers, inks, paints, sealants, PVC sols, acrylicsols and the like. Accordingly, calcium carbonate will be useful as arelatively inexpensive material for imparting thixotropy, if it whenadded could impart high degrees of viscosity and thixotropy.

DISCLOSURE OF THE INVENTION

A first object of the present invention is to provide a material forimparting thixotropy which comprises surface-treated calcium carbonate,which can impart a high degree of viscosity and a satisfactory degree ofthixotropy and which insures good storage stability.

A second object of the present invention is to provide a paste resincomposition containing surface-treated calcium carbonate which canimpart a high degree of viscosity and a satisfactory degree ofthixotropy.

The invention provides a material for imparting thixotropy comprised ofsurface-treated calcium carbonate. Characteristically, the material forimparting thixotropy exhibits a modal pore size peak at below 0.03 μmand a modal pore volume of 0.05–0.5 cm³/g on a pore size distributioncurve derived from mercury porosimetry.

Because the material for imparting thixotropy of the present inventioncomprises surface-treated calcium carbonate, it can be produced at arelatively low price. Also because the material for imparting thixotropyexhibits a modal pore size peak at below 0.03 μm and a modal pore volumeof 0.05–0.5 cm³/g on a pore size distribution curve derived from mercuryporosimetry, it shows superior dispersibility in polymeric materials andcan impart a high degree of viscosity and a satisfactory degree ofthixotropy to the polymeric materials. Also, polymeric materialscontaining the material for imparting thixotropy of the presentinvention show good storage stability.

Preferably, the surface-treated calcium carbonate in the presentinvention is the one that results from surface treatment of calciumcarbonate with an unsaturated fatty acid (A) and a saturated fatty acid(B). Also preferably, the calcium carbonate to be subjected to thesurface treatment has a BET specific surface area of 10–100 m²/g.

The unsaturated fatty acid (A) and saturated fatty acid (B) may be usedin the acid form, or alternatively in the form of a metal salt or ester,to effect the surface treatment. Each of the unsaturated fatty acid (A)and saturated fatty acid (B) preferably has a carbon cumber of 6–31.Also, the unsaturated fatty acid (A) and saturated fatty acid (B) arepreferably blended in the (A)/(B) ratio of 0.3–5.

A total amount of the unsaturated fatty acid (A) and saturated fattyacid (B) used to effect the surface treatment is preferably 1–50 partsby weight, based on 100 parts by weight of the calcium carbonate.

If the total amount of the unsaturated fatty acid (A) and saturatedfatty acid (B) used to effect the surface treatment is denoted by (C)parts by weight and the BET specific surface area of the calciumcarbonate by (D) m²/g, the (C)/(D) ratio is preferably 0.1–0.5.

The surface-treated calcium carbonate preferably has a moisture contentof 0.05–1.0%, when measured using a Karl Fischer moisture meter.

The paste resin composition of the present invention is characterized ascontaining surface-treated calcium carbonate which exhibits a modal poresize peak at below 0.03 μm and a modal pore volume of 0.05–0.5 cm³/g ona pore size distribution curve derived from mercury porosimetry.

Because the paste resin composition of the present invention containssuch surface-treated calcium carbonate, it can be produced at arelatively low cost. The surface-treated calcium carbonate, because ofits modal pore size peak at below 0.03 μm and its modal pore volume of0.05–0.5 cm³/g on a pore size distribution curve derived from mercuryporosimetry, shows superior dispersibility in the paste resincomposition which accordingly results in enjoying a high degree ofviscosity and satisfactory thixotropic properties. Also, the paste resincomposition of the present invention exhibits good storage stability.

The paste resin composition of the present invention can be used as asealant. Sealant is mostly used in joint portions, crack portions andair-gap glazing fitting portions of building, housing and otherarchitectural constructions to keep out air and moisture.

Examples of sealants include polyurethane, modified silicone, siliconeand polysulfide sealants. These sealants are classified into two types,i.e., one-part and two-part sealants, by their curing mechanisms.

The paste resin composition of the present invention may be in the formof a polyvinyl chloride sol or an acrylic sol. Polyvinyl chloride sol ismostly used as a noise insulation material at automobile tiresurroundings or vehicle bottoms and as a cushioning material at openingand closing portions of doors and trunks.

Acrylic sol is also used as a noise insulation material at automobiletire surroundings or vehicle bottoms and as a cushioning material atopening and closing portions of doors and trunks.

The present invention is below described in more detail.

(Calcium Carbonate Particles)

In the present invention, the calcium carbonate in the form of particlesfor use as a subject of surface treatment is not particularly limited intype, so long as it is useful as a filler for various polymericmaterial. Examples of calcium carbonates include natural calciumcarbonate (heavy calcium carbonate) and synthetic calcium carbonate(precipitated (colloidal) calcium carbonate). Natural calcium carbonateis produced directly from limestone ore and can be produced, forexample, by subjecting limestone ore to a sequence of mechanicalpulverization and classification.

Synthetic calcium carbonate is produced from calcium hydroxide and canbe produced, for example, by allowing calcium hydroxide to react with acarbon dioxide gas. Calcium hydroxide can be produced, for example, byallowing calcium oxide to react with water. Calcium oxide can beproduced, for example, by subjecting limestone ore, in combination withcoke or the like, to calcination. In this case, a carbon dioxide gas isgenerated during the calcination. Accordingly, calcium carbonate can beproduced by allowing the generated carbon dioxide gas to react withcalcium hydroxide.

The calcium carbonate for use in the present invention preferably has aBET specific surface area of 10–100 m²/g. The surface treatment ofcalcium carbonate, if its BET specific surface area is below 10 m²/g,may result in the difficulty to obtain surface-treated calcium carbonatewhich exhibits a modal pore size peak and a modal pore volume within therange specified in the present invention upon examination of a pore sizedistribution curve derived from mercury porosimetry. It is generallydifficult to produce calcium carbonate having a BET specific surfacearea of greater than 100 m²/g. The BET specific surface area of calciumcarbonate is more preferably 20–80 m²/g, still more preferably 30–60m²/g.

(Unsaturated Fatty Acid)

In the present invention, it is preferred that the calcium carbonate issurface-treated with both the unsaturated fatty acid (A) and thesaturated fatty acid (B) The unsaturated fatty acid refers to a fattyacid containing a double bond in a molecule and can be synthesized, forexample, by dehydration of a saturated fatty acid within a living body.The unsaturated fatty acid preferably has a carbon number of 6–31, morepreferably 8–26, still more preferably 9–21. Specific examples ofunsaturated fatty acids include obtusilic acid, caproleic acid,undecyleic acid, linderic acid, tsuzuic acid, physeteric acid,myristoleic acid, palmitoleic acid, petroslic acid, oleic acid, elaidicacid, asclepinic acid, vaccenic acid, gadoleic acid, gondoic acid,cetoleic acid, erucic acid, brassidic acid, selacholeic acid, ximenicacid, lumequeic acid, sorbic acid and linoleic acid. Particularlypreferred among them are oleic acid, erucic acid and linoleic acid.

In the surface treatment, the unsaturated fatty acid may be used in theoriginal acid form, or alternatively, in its metal salt and/or esterform. Examples of metal salts include alkaline metal salts and alkalineearth metal salts of unsaturated fatty acids. The use of water-solublemetal salts, among them, is preferred. Specific examples of metal saltsof unsaturated fatty acid include sodium, potassium and magnesium saltsof the above-listed unsaturated fatty acids. Sodium oleate, sodiumerucate and sodium linoleate are particularly useful.

Examples of esters are those of unsaturated fatty acids with loweraliphatic alcohols, including methyl esters, ethyl esters, propylesters, isopropyl esters, butyl esters, sec-butyl esters and tert-butylesters of unsaturated fatty acids.

The above-listed unsaturated fatty acids, metal salts and esters may beused alone or in combination.

(Saturated Fatty Acid)

The saturated fatty acid (B) is a fatty acid which has no double bond ina molecule. Natural fatty acids are mostly linear monobasic acids. Thesaturated fatty acid preferably has a carbon number of 6–31, morepreferably 8–26, still more preferably 9–21. Specific examples ofsaturated fatty acids include butyric acid, caproic acid, caprylic acid,pelargonic acid, capric acid, undecanoic acid, lauric acid, myristicacid, palmitic acid, stearic acid, arachic acid, behenic acid,lignoceric acid, cerotic acid, montanic acid and melissic acid. The useof palmitic acid, stearic acid and lauric acid, among them, ispreferred.

In the surface treatment, the saturated fatty acid may be used in itsoriginal acid form, or alternatively, in its metal salt and/or esterform. Examples of metal salts include alkaline metal salts and alkalineearth metal salts of saturated fatty acids. The use of water-solublemetal salts, among them, is preferred. Specific examples of metal saltsof saturated fatty acid include sodium, potassium and magnesium salts ofthe above-listed saturated fatty acids. Sodium palmitate, sodiumstearate and sodium laurate are particularly useful.

Examples of esters are those of saturated fatty acids with loweraliphatic alcohols, including methyl esters, ethyl esters, propylesters, isopropyl esters, butyl esters, sec-butyl esters and tert-butylesters of saturated fatty acids.

The above-listed saturated fatty acids, metal salts and esters may beused alone or in combination.

(Surface-treated Calcium Carbonate)

Surface-treated calcium carbonate is calcium carbonate having additionalproperty imparted as a result of surface treatment thereof. Examples oftreatment agents include, but not limited to, fatty acids such as (A)and (B); resin acids such as abietic acid, dehydroabietic acid anddihydroabietic acid; silane coupling agents such as vinylsilane,aminosilane and mercaptosilane; resins such as polyethylene,polypropylene and urethane resins; and polymeric dispersants. The use ofsaturated fatty acids and unsaturated fatty acids is preferred in thepresent invention.

The surface-treated calcium carbonate of the present invention exhibitsa modal pore size peak at below 0.03 μm and a modal pore volume of0.05–0.5 cm³/g on a pore size distribution curve derived from mercuryporosimetry. Fine particles of calcium carbonate readily formagglomerates which vary in size and number depending upon the surfacetreatment technique used. The modal pore size peak and modal pore volumevary in value with the sizes and number of such agglomerates. Thesurface treatment, when performed such that a modal pore size peak and amodal pore volume fall within the respective ranges specified in thepresent invention, results in the provision of the material forimparting thixotropy capable of imparting high viscosity and asatisfactory degree of thixotropy. A lower limit of the modal pore sizepeak is not particularly specified. However, it is generally hard toproduce surface-treated calcium carbonate which exhibits a modal poresize peak at below 0.002 μm. Accordingly, the modal pore size peak ismore preferably below 0.03 μm but not below 0.002 μm, still morepreferably in the range of 0.005–0.02 μm. The modal pore volume is morepreferably in the range of 0.1–0.3 cm³/g.

The pore size and pore volume of the surface-treated calcium carbonatecan be measured, for example, by using a mercury intrusion porosimeter(POROSIMETER 2000, product of Carlo Erba Instruments., Inc.). Forexample, measurement can be carried out under the conditions of amaximum intrusion pressure of 160 MPa·s and a threshold pore size of0.002 μm. The pore volume can be determined by a volume of mercuryforced into pores of calcium carbonate particles. The pore size can bedetermined by an intrusion pressure which forced the mercury into poresof calcium carbonate particles and a surface tension of the mercury. Amedian value of a modal pore size peak on a pore size distribution curveis taken as the modal pore size. Then, the modal pore volume can bedetermined as a pore volume included in this peak.

As stated above, the surface-treated calcium carbonate of the presentinvention preferably results from the surface treatment of calciumcarbonate with the unsaturated fatty acid (A) and saturated fatty acid(B). In this case, the unsaturated fatty acid (A) and saturated fattyacid (B) are preferably blended in the (A)/(B) ratio of 0.3–5. Thesurface treatment, if performed using a combination of the unsaturatedfatty acid (A) and saturated fatty acid (B) at the specified ratio,assures provision of the effect of the present invention that imparts ahigh degree of viscosity and a satisfactory degree of thixotropy. The(A)/(B) ratio is more preferably 0.7–4, still more preferably 1–2. Thetotal amount of the unsaturated fatty acid (A) and saturated fatty acid(B) used to effect the surface treatment is preferably 1–50 parts byweight, based on 100 parts by weight of the calcium carbonate. The useof such fatty acids in the surface treatment, if in the total amountwithin the specified range, assures provision of the effect of thepresent invention that imparts a high degree of viscosity and asatisfactory degree of thixotropy. The total amount of such fatty acidsused to effect the surface treatment is more preferably 3–30 parts byweight, still more preferably 6–20 parts by weight, based on 100 partsby weight of the calcium carbonate.

If the total amount of the unsaturated fatty acid (A) and saturatedfatty acid (B) used to effect the surface treatment is denoted by (C)parts by weight and the BET specific surface area of calcium carbonateby (D) m²/g, the (C)/(D) ratio is preferably 0.1–0.5, more preferably0.15–0.45, still more preferably 0.2–0.4. The paste resin composition,if using calcium carbonate with its surface being treated with the fattyacids in the specified total amount, assures provision of the effect ofthe present invention that imparts a high degree of viscosity and asatisfactory degree of thixotropy.

A composition of the surface treatment agent in the surface-treatedcalcium carbonate can be determined as by a gas chromatography. Theamount of the surface treatment agent contained therein can bedetermined as by differential thermal analysis.

The drying process in the production, if carried out to reduce amoisture content to a low level, increases a cost. On the other hand, ifit is carried out to leave a moisture content at an excessively highlevel, a problem such as poor storage stability arises when it isformulated into the paste resin composition. It is therefore desirablethat the surface-treated calcium carbonate is maintained at a propermoisture content level, preferably in the range of 0.05–1.0%, morepreferably 0.1–0.9%, still more preferably 0.2–0.8%, when measured by aKarl Fischer moisture content meter. The use of the surface-treatedcalcium carbonate having a moisture content within the specified rangeresults in imparting good storage stability.

(Production of Surface-treated Calcium Carbonate)

Surface-treated calcium carbonate is calcium carbonate having additionalproperty imparted as a result of surface treatment thereof. Examples oftreatment agents include, but not limited to, fatty acids such as (A)and (B); resin acids such as abietic acid, dehydroabietic acid anddihydroabietic acid; silane coupling agents such as vinylsilane,aminosilane and mercaptosilane; resins such as polyethylene,polypropylene and urethane resins; and polymeric dispersants. The use ofsaturated fatty acids and unsaturated fatty acids is preferred in thepresent invention.

The surface-treated calcium carbonate can be produced, for example, byadding a surface treatment agent to an aqueous slurry of calciumcarbonate particles, stirring and then dewatering the slurry. Where theunsaturated fatty acid (A) and saturated fatty acid (B) are used, theymay be added in the form of a mixture. The calcium carbonate solidscontent in the aqueous slurry may be suitably adjusted, e.g., dependingon the dispersibility of the calcium carbonate particles, ease ofdewatering and sizes of the calcium carbonate particles. The aqueousslurry shows a proper degree of viscosity when its solids content isadjusted generally to 2–30 weight %, preferably 5–20 weight %. Use of anexcessively large quantity of water is disadvantageous because it makesdewatering difficult and increases a drainage load.

The unsaturated fatty acid (A) and saturated fatty acid (B) while in theacid form are generally difficult to disperse quickly in the aqueousslurry. Accordingly, it is generally preferred that they are saponifiedto form sodium or potassium salts for addition to the aqueous slurry ofcalcium carbonate.

According to another method for production of the surface-treatedcalcium carbonate, dried calcium carbonate particles are stirred in astirring and mixing machine, such as a Henschel mixer, to which asurface treatment agent is added. This method becomes advantageous whencalcium carbonate has a relatively large particle size.

(Polymeric Material)

The surface-treated calcium carbonate of the present invention, whenloaded as a filler in polymeric materials such as inks, paints,sealants, PVC sols and acrylic sols, can impart a high degree ofviscosity and a satisfactory degree of thixotropy thereto, as well asinsuring good storage stability. The amount of the surface-treatedcalcium carbonate to be loaded in polymeric materials is suitably chosendepending on the loading purpose, characteristic properties sought forsuch polymeric materials and the others.

For example, the surface-treated calcium carbonate can be made into anink formulation in the general amount of about 5–100 parts by weight,based on 100 parts by weight of an ink resin component; a paintformulation in the general amount of about 5–100 parts by weight, basedon 100 parts by weight of a paint resin component; a sealing mediumformulation, e.g., a silicone resin sealing medium in the general amountof about 5–400 parts by weight, based on 100 parts by weight of asealing medium resin component; a PVC sol formulation in the generalamount of about 5–400 parts by weight, based on 100 parts by weight of aPVC sol resin component; or an acrylic sol formulation in the generalamount of about 5–400 parts by weight, based on 100 parts by weight ofan acrylic sol resin component.

(Polyurethane Sealant)

The paste resin composition of the present invention may be formulatedto constitute a polyurethane sealant which mainly contains isocyanate,polyol, plasticizer, filler and other additives.

Examples of isocyanates include tolylene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate,tolidine diisocyanate (TODI), xylene diisocyanate, hexamethylenediisocyanate and modified products thereof; dicyclohexylmethanediisocyanate (hydrogenated MDI); isophorone diisocyanate (IPDI); and thelike.

Examples of polyols include dicarboxylic acids such as adipic acid,phthalic acid, sebacic acid and dimer acid; glycols such as ethyleneglycol, diethylene glycol, propylene glycol, butylene glycol,1,3-butanediol, hexanetriol and trimethylol-propane; and the like. Otherpolyols include esters of the type formed via ring-openingpolymerization of caprolactone.

Examples of plasticizers include dimethyl phthalate (DMP), diethylphthalate (DEP), di-n-butyl phthalate (DBP), diheptyl phthalate (DHP),dioctyl phthalate (DOP), diisononyl phthalate (DINP), diisodecylphthalate (DIDP), di-tridecyl phthalate (DTDP), butyl benzyl phthalate(BBP), dicyclohexyl phthalate (DCHP), tetrahydrophthalate ester, dioctyladipate (DOA), diisononyl adipate (DINA), diisodecyl adipate (DIDA),di-n-alkyl adipate, dibutyl diglycol adipate (BXA), bis(2-ethylhexyl)azelate (DOZ), dibutyl sebacate (DBS), dioctyl sebacate (DOS), dibutylmaleate (DBM), di-2-ethylhexyl maleate (DOM), dibutyl fumarate (DBF),tricresyl phosphate (TCP), triethyl phosphate (TEP), tributyl phosphate(TBP), tris(2-ethylhexyl) phosphate (TOP), tris (chloroethyl) phosphate(TCEP), tris (dichloropropyl) phosphate (CRP), tributoxyethyl phosphate(TBXP), tris(β-chloropropyl) phosphate (TMCPP), triphenyl phosphate(TPP), octyl diphenyl phosphate (CDP), acetyl triethyl citrate, acetyltributyl citrate and the like. Others include trimellitic acidplasticizers, polyester plasticizers, chlorinated paraffin, stearic acidplasticizers and dimethyl polysiloxane.

Examples of fillers (including thickeners) include organic and inorganicfillers. Examples of inorganic fillers include calcium carbonate(natural and synthetic products), calcium-magnesium carbonate (naturaland synthetic products), basic magnesium carbonate, quartz powder,silica stone powder, fine particle silicic acid (products obtained bydry, wet and gel processes), fine particle calcium silicate, fineparticle aluminum silicate, kaolin clay, pyrophyllite clay, talc,sericite, mica, bentonite, nepheline syenite, aluminum hydroxide,magnesium hydroxide, barium sulfate, carbon black (furnace, thermal andacetylene), graphite and the like. Examples of needle-like and fibrousinorganic fillers include sepiolite, wollastonite, xonotlite, potassiumtitanate, carbon fibers, mineral fibers, glass fibers, shirasu balloons,fly ash balloons, glass balloons, silica beads, alumina beads, glassbeads and the like. Examples of powder- and bead-form organic fillersinclude wood powder, walnut powder, cork powder, flour, starch, ebonitepowder, rubber powder, lignin, phenolic resins, high styrene resins,polyethylene resins, silicone resins, urea resins, and the like.Examples of fibrous organic fillers include cellulose powder, pulppowder, synthetic fiber powder, amide wax, castor oil wax, and the like.

The surface-treated calcium carbonate is preferably loaded in the pasteresin composition of the present invention in the amount of 5–400 partsby weight, more preferably 10–300 parts by weight, based on 100 parts byweigh of all of resin components (including a plasticizer) and liquidadditives.

In the case where the paste resin composition constitutes a polyurethanesealant, the surface-treated calcium carbonate is preferably loadedtherein in the above-specified amount, based on 100 parts by weight ofall of the isocyanate, polyol, plasticizer and liquid additives.

(Modified Silicone Sealant)

The paste resin composition of the present invention may be formulatedto constitute a modified silicone sealant which primarily contains amodified silicone resin, a plasticizer, a filler and other additives.

One useful modified silicone resin can be produced, for example, byconverting a terminal hydroxyl group of polyoxy propylene glycol to analkoxide group, subjecting to a reaction with a polyhalogen compound toincrease a molecular weight, subjecting to a chain extending reaction tofurther increase a molecular weight, subjecting to a reaction with anorganic halogen compound represented by CH₂═CHRX to introduce anolefinic group at a terminal end, subjecting to a dehalogenatingpurification process, and subjecting to hydrosilylation to introduce areactive silicone functional group at a terminal end.

Examples of useful plasticizers, fillers and other additives are listedabove as applicable to the polyurethane sealant.

In the case where the paste resin composition constitutes a modifiedsilicone sealant, the surface-treated calcium carbonate is preferablyloaded therein in the amount of 5–400 parts by weight, more preferably10–300 parts by weight, based on 100 parts by weight of all of themodified silicone resin, plasticizer and liquid additives.

(Silicone Sealant)

The paste resin composition of the present invention may be formulatedto constitute a silicone sealant which primarily contains a siliconeresin, a crosslinking agent, a plasticizer, a filler and otheradditives.

One useful silicone resin can be produced as follows. Silicon dioxide isreduced in an electric furnace to obtain metallic silicon (Si) which issubsequently ground. The ground metallic silicon is reacted with methylchloride (CH₃Cl) at a high temperature in the presence of a coppercatalyst to synthesize crude chlorosilane ((CH₃)_(n)SiCl_(4−n)) which isthen rectified to collect dimethyldichlorosilane ((CH₃)₂SiCl₂). Thedimethyldichlorosilane condenses upon hydrolysis into a cyclic structureand a hydroxyl-containing linear structure. Polymerization of such astructure, either cyclic or linear, in the presence of H₂O and analkaline or acid catalyst results in provision of a silicone resinhaving hydroxyl group at each terminal end.

Useful crosslinking agents are silane or siloxane compounds containingat least two hydrolyzable functional groups. Examples include those ofdeoximation type, deacetic acid type, dealcoholation type, deamidationtype and dehydroxylamination type; ground organopolysiloxane; and thelike.

Examples of useful plasticizers, fillers and other additives are listedabove as applicable to the polyurethane sealant.

In the case where the paste resin composition constitutes a siliconesealant, the surface-treated calcium carbonate is preferably loadedtherein in the amount of 5–400 parts by weight, more preferably 10–300parts by weight, based on 100 parts by weight of all of the siliconeresin, crosslinking agent, plasticizer and liquid additives.

(Polysulfide Sealant)

The paste resin composition of the present invention may be formulatedto constitute a polysulfide sealant which primarily contains apolysulfide resin, a plasticizer, a filler and other additives.

One useful polysulfide resin can be produced as follows. Ethylene oxideand hydrochloric acid are reacted to produce ethylene chlorohydrin whichis subsequently reacted with paraformaldehyde to obtaindichloroethylformal as a starting material. The thus-obtaineddichloroformal is added with stirring and heating to a colloidalsuspension containing sodium polysulfide, a small amount of activatorand magnesium hydroxide to produce the polysulfide resin.

It is a recent trend to use a modified polysulfide resin having an SHgroup (mercapto group) at its molecular end and a urethane bond in itsmain chain.

Examples of useful plasticizers, fillers and other additives are listedabove as applicable to the polyurethane sealant.

In the case where the paste resin composition constitutes a polysulfidesealant, the surface-treated calcium carbonate is preferably loadedtherein in the amount of 5–400 parts by weight, more preferably 10–300parts by weight, based on 100 parts by weight of all of the polysulfideresin (modified polysulfide resin), plasticizer and liquid additives.

(Vinyl Chloride Sol)

The paste resin composition of the present invention may be formulatedto constitute a vinyl chloride sol which primarily contains a vinylchloride resin, a plasticizer, a filler and other additives. Examples ofuseful plasticizers, fillers and other additives are listed above asapplicable to the polyurethane sealant.

In the case where the paste resin composition constitutes a vinylchloride sol, the surface-treated calcium carbonate is preferably loadedtherein in the amount of 5–400 parts by weight, more preferably 10–300parts by weight, based on 100 parts by weight of all of the vinylchloride resin, plasticizer and liquid additives.

(Acrylic Sol)

The paste resin composition of the present invention may be formulatedto constitute an acrylic sol which primarily contains an acrylic resin,a crosslinking agent, a plasticizer, a filler and other additives.

Examples of monomers useful for constituting the acrylic resin aremethacrylic monomers which can be roughly classified into nonfunctional,monofunctional and polyfunctional ones. Examples of nonfunctionalmonomers include methyl methacrylate, ethyl methacrylate, propylmethacrylate, butyl methacrylate, isobutyl methacrylate, tert-butylmethacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecylmethacrylate, lauryl methacrylate, lauryl-tridecyl methacrylate,tridecyl methacrylate, cetyl-stearyl methacrylate, stearylmeth-acrylate, cyclohexyl methacrylate, benzyl methacrylate and thelike. Examples of mononfunctional monomers include methacrylic acid,2-hydroxyethyl methacrylate, 2-hydroxy-propyl methacrylate,dimethylaminoethyl methacrylate, di-ethylaminoethyl methacrylate,tert-butylaminoethyl meth-acrylate, glycidyl methacrylate,tetrahydrofurfuryl meth-acrylate and the like. Examples ofpolyfunctional monomers include ethylene di-methacrylate, diethyleneglycol di-methacrylate, triethylene glycol dimethacrylate,tetra-ethylene glycol dimethacrylate, decaethylene glycoldi-methacrylate, pentadecaethylene glycol dimethacrylate,pentacontahectaethylene glycol dimeth-acrylate, 1,3-butylenedimethacrylate, allyl methacrylate, trimethylolpropane tri-methacrylate,pentaerythritol tetramethacrylate, phthalic acid ethylene glycoldimethacrylate and the like. The acrylic resin can be produced bycopolymerization of the above-listed nonfunctional monomers with theabove-listed monofunctional monomers and/or polyfunctional monomers.

Examples of crosslinking agents include amino resins, isocyanatecompounds, epoxy resins and the like. Examples of useful plasticizersand fillers are listed above as applicable to the polyurethane sealant.

In the case where the paste resin composition constitutes an acrylicsol, the surface-treated calcium carbonate is preferably loaded thereinin the amount of 5–400 parts by weight, more preferably 10–300 parts byweight, based on 100 parts by weight of all of the acrylic resin,plasticizer and liquid additives.

BEST MODE FOR CARRYING OUT THE PRESENT INVENTION

The present invention is below described in more detail by way ofExamples. It will be recognized that the present invention is notlimited to the following examples. Suitable changes and modificationscan be effected without departing from the scope of the presentinvention.

(Preparation of Surface-treated Calcium Carbonate)

EXAMPLE 1

Water controlled at 80° C. was added to 2 kg of synthetic calciumcarbonate having a BET specific surface area of 40 m²/g such that asolids content by weight was brought to 10%. The mixture was stirred ina media stirring disperser to prepare an aqueous slurry of calciumcarbonate. 200 g of mixed fatty acid (containing 100 g oleic acid and100 g stearic acid), with a saponified oleic acid/stearic acidratio=1.0, was added to the aqueous slurry while stirred in thedisperser. After 5 minutes of stirring, the aqueous slurry was dewateredby pressing. The dewatered cake was dried and finely divided to obtainabout 2 kg of surface-treated calcium carbonate as a result of surfacetreatment of the calcium carbonate with the unsaturated fatty acid andsaturated fatty acid.

The BET specific surface area was measured using a specific surface areameasurement apparatus FlowSorb II 2300 (product of Micromeritics Corp.).

EXAMPLE 2

The procedure of Example 1 was followed, except that synthetic calciumcarbonate having a BET specific surface area of 25 m²/g was used, toproduce surface-treated calcium carbonate as a result of surfacetreatment of the calcium carbonate with the unsaturated fatty acid andsaturated fatty acid.

EXAMPLE 3

200 g of mixed fatty acid (containing 67 g oleic acid and 133 g stearicacid) at the oleic acid/stearic acid ratio=0.5 was used. Otherwise, theprocedure of Example 1 was followed to produce surface-treated calciumcarbonate as a result of surface treatment of the calcium carbonate withthe unsaturated fatty acid and saturated fatty acid.

EXAMPLE 4

200 g of mixed fatty acid (containing 130 g oleic acid and 70 g stearicacid) at the oleic acid/stearic acid ratio=1.9 was used. Otherwise, theprocedure of Example 1 was followed to produce surface-treated calciumcarbonate as a result of surface treatment of the calcium carbonate withthe unsaturated fatty acid and saturated fatty acid.

EXAMPLE 5

200 g of mixed fatty acid (containing 100 g oleic acid and 100 gpalmitic acid) at the oleic acid/palmitic acid ratio=1.0 was used.Otherwise, the procedure of Example 1 was followed to producesurface-treated calcium carbonate as a result of surface treatment ofthe calcium carbonate with the unsaturated fatty acid and saturatedfatty acid.

EXAMPLE 6

200 g of mixed fatty acid (containing 100 g oleic acid, 50 g stearicacid and 50 g palmitic acid) at the oleic acid/(stearic acid+palmiticacid) ratio=1.0 was used. Otherwise, the procedure of Example 1 wasfollowed to produce surface-treated calcium carbonate as a result ofsurface treatment of the calcium carbonate with the unsaturated fattyacid and saturated fatty acid.

EXAMPLE 7

200 g of mixed fatty acid (containing 100 g oleic acid, 50 g stearicacid and 50 g lauric acid) at the oleic acid/(stearic acid+lauric acid)ratio=1.0 was used. Otherwise, the procedure of Example 1 was followedto produce surface-treated calcium carbonate as a result of surfacetreatment of the calcium carbonate with the unsaturated fatty acid andsaturated fatty acid.

EXAMPLE 8

200 g of mixed fatty acid (containing 100 g oleic acid, 34 g stearicacid, 33 g palmitic acid and 33 g lauric acid) at the oleicacid/(stearic acid+palmitic acid+lauric acid) ratio=1.0 was used.Otherwise, the procedure of Example 1 was followed to producesurface-treated calcium carbonate as a result of surface treatment ofthe calcium carbonate with the unsaturated fatty acid and saturatedfatty acid.

EXAMPLE 9

200 g of mixed fatty acid (containing 80 g oleic acid, 20 g linoleicacid, 34 g stearic acid, 33 g palmitic acid and 33 g lauric acid) at the(oleic acid+linoleic acid)/(stearic acid+palmitic acid+lauric acid)ratio=1.0 was used. Otherwise, the procedure of Example 1 was followedto produce surface-treated calcium carbonate as a result of surfacetreatment of the calcium carbonate with the unsaturated fatty acid andsaturated fatty acid.

COMPARATIVE EXAMPLE 1

The procedure of Example 1 was followed, except that 2 kg of syntheticcalcium carbonate having a BET specific surface area of 15 m²/g wasused, to produce surface-treated calcium carbonate as a result ofsurface treatment of the calcium carbonate with the unsaturated fattyacid and saturated fatty acid.

COMPARATIVE EXAMPLE 2

60 g of mixed fatty acid (containing 30 g oleic acid and 30 g stearicacid) at the oleic acid/stearic acid ratio=1.0 was used. Otherwise, theprocedure of Example 1 was followed to produce surface-treated calciumcarbonate as a result of surface treatment of the calcium carbonate withthe unsaturated fatty acid and saturated fatty acid.

COMPARATIVE EXAMPLE 3

The procedure of Example 1 was followed, except that the oleicacid/stearic acid ratio=0 was chosen, i.e., oleic acid was excluded andonly stearic acid was used in the amount of 200 g, to producesurface-treated calcium carbonate as a result of surface treatment ofthe calcium carbonate with the unsaturated fatty acid and saturatedfatty acid.

(Powder Test)

The surface-treated calcium carbonates obtained in Examples 1–9 andComparative Examples 1–3 were measured for modal pore size and modalpore volume, using a mercury intrusion porosimeter under the conditionsof a maximum intrusion pressure of 160 MPa·s and a threshold pore sizeof 0.002 μm

Also, a total amount of the unsaturated fatty acid and saturated fattyacid that effected the surface treatment was measured by differentialthermal analysis. An unsaturated fatty acid/saturated fatty acid ratiowas also measured for each surface-treated calcium carbonate, using gaschromatography. The results are shown in Table 1.

Also, a value for (C)/(D) is shown in Table 1, when the total amount ofthe unsaturated fatty acid and saturated fatty acid used in the surfacetreatment is given by (C) parts by weight and the BET specific surfacearea of each calcium carbonate by (D) m²/g.

A moisture content of each surface-treated calcium carbonate is alsoshown in Table 1, when measured with a Karl Fisher moisture meter.

TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Pore Size Distribution ModalPore Size(μm) 0.016 0.028 0.026 0.018 0.016 0.016 Modal PoreVolume(cm³/g) 0.20 0.23 0.15 0.21 0.20 0.19 Amount of Fatty Acids 10.19.5 9.8 9.9 10.0 9.9 (parts by weight) Unsaturated/Saturated 1.1 1.0 0.51.9 1.0 1.0 Fatty Acid (C)/(D) 0.30 0.40 0.31 0.29 0.31 0.28 KarlFischer Moisture 0.51 0.50 0.52 0.48 0.47 0.55 Content (%) Ex. 7 Ex. 8Ex. 9 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Pore Size Distribution ModalPore Size(μm) 0.018 0.020 0.016 0.066 0.050 0.088 Modal PoreVolume(cm³/g) 0.21 0.20 0.21 0.22 0.19 0.10 Amount of Fatty Acids 9.59.6 9.8 9.9 3.1 10.0 (P.B.W.) Unsaturated/Saturated 1.1 1.0 1.0 1.0 1.10 Fatty Acid (C)/(D) 0.26 0.27 0.29 0.71 0.09 0.32 Karl Fischer Moisture0.58 0.56 0.53 0.35 0.12 0.78 Content (%)

(DOP Sol Viscosity Test)

Each of the surface-treated calcium carbonates obtained in Examples 1–9and Comparative Examples 1–3 was formulated into a DOP sol and itsviscosity was subsequently measured. 200 g of the surface-treatedcalcium carbonate and 200 g of DOP (dioctyl phthalate, product of J-PlusCo., Ltd.) were fully mixed to provide the DOP sol which was thenmeasured for initial viscosity at 20° C. Also, its viscosity after 120°C.×7 days was measured at 20 ° C. Viscosity measurement was performedusing a BH viscometer (product of Tokimec, Inc.) at 2 rpm and 20 rpm.The measurement results are shown in Table 2. A rate of viscosityincrease refers to a ratio in percentage of the viscosity after 7 daysto the viscosity immediately after the mixing.

TABLE 2 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Immediately After Mixing  2rpm(Pa · s) 3220 1220 1300 2990 3300 3000 20 rpm(Pa · s) 419 163 210 380452 401  2 rpm/20 rpm 7.7 7.5 6.2 7.9 7.3 7.5 After 7 Days  2 rpm(Pa ·s) 3250 1300 1520 2970 3420 3100 20 rpm(Pa · s) 420 175 253 380 475 419 2 rpm/20 rpm 7.7 7.4 6.0 7.8 7.2 7.4 Rate of Viscosity Increase  2rpm(%) 101 107 117 100 104 103 20 rpm(%) 100 107 120 100 105 104 Ex. 7Ex. 8 Ex. 9 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Immediately After Mixing 2 rpm(Pa · s) 2520 2830 3100 910 400 72 20 rpm(Pa · s) 327 382 408 12558 15  2 rpm/20 rpm 7.7 7.4 7.6 7.3 6.9 4.8 After 7 Days  2 rpm(Pa · s)2600 2800 3050 930 590 95 20 rpm(Pa · s) 339 378 407 130 88 23  2 rpm/20rpm 7.7 7.4 7.5 7.2 6.7 4.1 Rate of Viscosity Increase  2 rpm(%) 103 9998 102 148 132 20 rpm(%) 104 99 100 104 152 153

As can be clearly seen from the results shown in Table 2, the DOP solsprepared using the surface-treated calcium carbonates of Examples 1–9 inaccordance with the present invention exhibit high viscosity levels andgood thixotropic properties. They also exhibit good storage stability.

A DOP sol is contained in most sealants as a plasticizer and itsviscosity is generally correlated to a viscosity of the sealantcontaining it. Accordingly, it can be argued that sealants, if preparedusing any of the surface-treated calcium carbonates of Examples 1–9 inaccordance with the present invention, also exhibit high viscositylevels and satisfactory thixotropic properties.

(Viscosity Test of PPG Sol)

Each of the surface-treated calcium carbonates obtained in Examples 1–9and Comparative Examples 1–3 was formulated into a PPG (polypropyeleneglycol) sol and its viscosity was subsequently measured. 200 g of thesurface-treated calcium carbonate and 200 g of PPG (polypropyleneglycol, product name “SUMIPHEN 3086”, product of Sumitomo Bayer UrethaneCo., Ltd.) were fully mixed to provide the PPG sol. A viscosity of theresulting PPG sol both initially and after 7 days was measured in thesame manner as described above. The measurement results are shown inTable 3.

TABLE 3 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Immediately After Mixing  2rpm(Pa · s) 4070 2710 1960 3780 4150 3680 20 rpm(Pa · s) 527 358 277 480555 480  2 rpm/20 rpm 7.7 7.6 7.1 7.9 7.5 7.6 After 7 Days  2 rpm(Pa ·s) 4060 2750 2510 3600 4200 3700 20 rpm(Pa · s) 528 362 349 460 568 492 2 rpm/20 rpm 7.7 7.6 7.2 7.8 7.8 7.5 Rate of Viscosity Increase  2rpm(%) 100 101 128 95 101 101 20 rpm(%) 100 101 126 96 102 103 Ex. 7 Ex.8 Ex. 9 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Immediately After Mixing  2rpm(Pa · s) 3880 3540 3780 910 380 40 20 rpm(Pa · s) 504 448 480 125 6313  2 rpm/20 rpm 7.7 7.9 7.9 7.3 6.0 3.1 After 7 Days  2 rpm(Pa · s)3990 3500 3600 920 510 63 20 rpm(Pa · s) 518 449 460 126 89 21  2 rpm/20rpm 7.7 7.8 7.8 7.3 5.7 3.0 Rate of Viscosity Increase  2 rpm(%) 103 9995 101 134 158 20 rpm(%) 103 100 96 101 141 162

As can be clearly seen from Table 3, the PPG sols prepared using thesurface-treated calcium carbonates of Examples 1–9 in accordance withthe present invention exhibit high viscosity levels and good thixotropicproperties. They also exhibit good storage stability.

A two-part polyurethane sealant generally uses a PPG sol as a curingagent and its viscosity is well correlated to a viscosity of the PPGsol. Accordingly, it can be argued that two-part polyurethane sealants,if prepared using any of the surface-treated calcium carbonates ofExamples 1–9 in accordance with the present invention, also exhibit highviscosity levels and good thixotropic properties.

(Viscosity Test of One-part Modified Silicone Sealant)

Each of the surface-treated calcium carbonates obtained in Examples 1–9and Comparative Examples 1–3 was formulated into a one-part modifiedsilicone sealant and its viscosity was subsequently measured. 85 g ofHakuenka CCR (product of Shiraishi Kogyo Co., Ltd.), 100 g of a modifiedsilicone polymer (product name “MS POLYMER S203”, product of KanekaCorp.), 50 g of DOP, 35 g of heavy calcium carbonate (product name“WHITON 305”, product of Shiraishi Kogyo Co., Ltd.), 15 g of thesurface-treated calcium carbonate, 3.4 g of trimethoxy-vinylsilane(product name “KBM #1003”, product of Shin-Etsu chemical Co., Ltd.) and2.5 g of a catalyst (product name “#918”, product of Sankyo OrganicChemicals Co., Ltd.) were fully mixed to prepare the one-part modifiedsilicone sealant. A viscosity of the resulting one-part modifiedsilicone sealant both initially and after 7 days was measured in thesame manner as described above. The measurement results are shown inTable 4.

TABLE 4 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Immediately After Mixing  2rpm(Pa · s) 1008 778 802 980 1100 1060 20 rpm(Pa · s) 173 139 164 166185 183  2 rpm/20 rpm 5.8 5.6 4.9 5.9 5.9 5.8 After 7 Days  2 rpm(Pa ·s) 1180 900 1002 1117 1265 1230 20 rpm(Pa · s) 219 179 213 208 224 227 2 rpm/20 rpm 5.4 5.0 4.7 5.4 5.6 5.4 Rate of Viscosity Increase  2rpm(%) 117 117 125 114 115 116 20 rpm(%) 127 129 130 125 121 124 Ex. 7Ex. 8 Ex. 9 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Immediately After Mixing 2 rpm(Pa · s) 990 1200 1150 580 172 890 20 rpm(Pa · s) 166 218 209 10249 231  2 rpm/20 rpm 6.0 5.5 5.5 5.8 3.5 3.9 After 7 Days  2 rpm(Pa · s)1099 1380 1357 673 230 1068 20 rpm(Pa · s) 199 266 270 128 68 291  2rpm/20 rpm 6.3 5.2 5.0 5.3 3.4 3.7 Rate of Viscosity Increase  2 rpm(%)111 115 118 116 134 120 20 rpm(%) 120 122 129 125 138 126

As can be clearly seen from Table 4, the one-part modified siliconesealants prepared using the surface-treated calcium carbonates ofExamples 1–9 in accordance with the present invention exhibit highviscosity levels and good thixotropic properties. They also exhibit goodstorage stability.

(Viscosity Test of Two-part Modified Silicone Sealant)

Each of the surface-treated calcium carbonates obtained in Examples 1–9and Comparative Examples 1–3 was formulated into a two-part modifiedsilicone sealant and its viscosity was subsequently measured. Thetwo-part modified silicone sealant consisted of a base material and acuring agent. Used as the base material was a mixture containing 120 gof Hakuenka CCR (product of Shiraishi Kogyo Co., Ltd.), 35 g of amodified silicone polymer (product name “MS POLYMER S203”, product ofKaneka Corp.), 50 g of DOP, 20 g of heavy calcium carbonate (productname “WHITON P-30”, product of Shiraishi Kogyo Co., Ltd.), 15 g of thesurface-treated calcium carbonate and 5 g of EPICOAT 828 (product ofYuka-Shell Epoxy Co., Ltd.). Used as the curing agent was a mixturecontaining 20 g of heavy calcium carbonate (product name “WHITON P-30”,product of Shiraishi Kogyo Co., Ltd.), 6.3 g of DOP, 3 g of tin octylate(product) and 0.7 g of laurylamine. Each of the base material and curingagent was fully mixed. A viscosity of the resulting base material bothinitially and after 7 days was measured and further a viscosity of thetwo-part modified silicone sealant immediately after the base materialand curing agent were mixed together was measured in the same manner asdescribed above. In this particular evaluation, a viscosity value wasmeasured by a BH viscometer at 1 rpm and 10 rpm. The measurement resultsare shown in Table 5.

TABLE 5 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Base Material Viscosity(Immediately After Mixing)  1 rpm(Pa · s) 1820 1610 1790 1780 1850 183010 rpm(Pa · s) 323 288 326 312 328 330  1 rpm/10 rpm 5.6 5.6 5.5 5.7 5.75.5 Sealant Viscosity (Immediately After Mixing)  1 rpm(Pa · s) 18501580 1810 1790 1820 1840 10 rpm(Pa · s) 292 287 335 314 327 333  1rpm/10 rpm 5.5 5.5 5.4 5.7 5.6 5.5 Ex. 7 Ex. 8 Ex. 9 Comp. Ex. 1 Comp.Ex. 2 Comp. Ex. 3 Immediately After Mixing  1 rpm(Pa · s) 1780 1880 17701510 1330 1340 10 rpm(Pa · s) 320 342 318 274 238 280  1 rpm/10 rpm 5.65.5 5.6 5.5 5.6 4.8 Sealant Viscosity (Immediately After Mixing)  1rpm(Pa · s) 1800 1900 1800 1560 1210 1350 10 rpm(Pa · s) 328 349 318 280220 296  1 rpm/10 rpm 5.5 5.4 5.7 5.6 5.5 4.6

As can be clearly seen from Table 5, the two-part modified siliconesealants and their base materials prepared using the surface-treatedcalcium carbonates of Examples 1–9 in accordance with the presentinvention exhibit high viscosity levels and good thixotropic properties.They also exhibit good storage stability.

(Viscosity Test of Silicone Sol)

Each of the surface-treated calcium carbonates obtained in Examples 1–9and Comparative Examples 1–3 was formulated into a silicone sol and itsviscosity was subsequently measured. 200 g of the surface-treatedcalcium carbonate and 200 g of a silicone oil (product name “TSF451–1M”, product of GE Toshiba Silicones Co., Ltd.) were fully mixed toprepare the silicone sol. A viscosity of the resulting silicone sol bothinitially and after 7 days was measured in the same manner as describedabove. The measurement results are shown in Table 6.

TABLE 6 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Immediately After Mixing  2rpm(Pa · s) 410 350 405 380 390 400 20 rpm(Pa · s) 87 78 88 79 83 83  2rpm/20 rpm 4.7 4.5 4.6 4.8 4.7 4.8 After 7 Days  2 rpm(Pa · s) 420 370410 400 400 410 20 rpm(Pa · s) 90 81 90 85 86 89  2 rpm/20 rpm 4.7 4.64.6 4.7 4.7 4.6 Rate of Viscosity Increase  2 rpm(%) 102 106 101 105 103103 20 rpm(%) 103 104 102 108 106 107 Ex. 7 Ex. 8 Ex. 9 Comp. Ex. 1Comp. Ex. 2 Comp. Ex. 3 Immediately After Mixing  2 rpm(Pa · s) 400 420410 210 130 280 20 rpm(Pa · s) 85 92 90 47 30 70  2 rpm/20 rpm 4.7 4.64.6 4.5 4.3 4.0 After 7 Days  2 rpm(Pa · s) 410 420 420 220 190 310 20rpm(Pa · s) 88 95 91 51 42 76  2 rpm/20 rpm 6.3 4.4 4.6 4.3 4.7 4.1 Rateof Viscosity Increase  2 rpm(%) 103 100 102 105 146 110 20 rpm(%) 104103 101 109 140 109

As can be clearly seen from Table 6, the silicone sols prepared usingthe surface-treated calcium carbonates of Examples 1–9 in accordancewith the present invention exhibit increased viscosity levels andimproved thixotropic properties, compared to the silicone sols preparedusing the surface-treated calcium carbonates of Comparative Examples1–3. As also can be seen, they also exhibit superior storage stability.

Generally, a silicone sealant is well correlated in viscosity to thesilicone sol. Accordingly, it can be argued that silicone sealants, ifprepared using any of the surface-treated calcium carbonates of Examples1–9 in accordance with the present invention, also exhibit highviscosity levels and good thixotropic properties.

(Viscosity Test of Polyvinyl Chloride Sol)

Each of the surface-treated calcium carbonates obtained in Examples 1–9and Comparative Examples 1–3 was formulated into a polyvinyl chloridesol and its viscosity was subsequently measured. 200 g of thesurface-treated calcium carbonate, 300 g of a polyvinyl chloride resin(product name “ZEST P21”, product of Shin Daiichi Vinyl Chloride Co.),300 g of DINP, 150 g of heavy calcium carbonate (product name “WHITONP-30”, product of Shiraishi Kogyo Co., Ltd.), 10 g of a tackifier(product name “BARSAMIDE 140”, product of Henkel Japan Ltd.) and 40 g ofa diluent (product name “MINERAL TURPEN”, product of Yamakei Sangyo Co.,LTd.) were fully mixed to prepare the polyvinyl chloride sol. Aviscosity of the resulting polyvinyl chloride sol both initially andafter 7 days was measured in the same manner as described above. Themeasurement results are shown in Table 7.

TABLE 7 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Immediately After Mixing  2rpm(Pa · s) 1040 740 750 1000 1200 1160 20 rpm(Pa · s) 169 116 146 156198 190  2 rpm/20 rpm 6.2 6.4 5.1 6.4 6.1 6.1 After 7 Days  2 rpm(Pa ·s) 1050 760 930 980 1310 1210 20 rpm(Pa · s) 168 118 169 153 218 198  2rpm/20 rpm 6.3 6.4 5.5 6.4 6.0 6.1 Rate of Viscosity Increase  2 rpm(%)101 103 124 98 109 104 20 rpm(%) 99 102 116 98 110 104 Ex. 7 Ex. 8 Ex. 9Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Immediately After Mixing  2 rpm(Pa ·s) 980 990 1050 570 150 6.2 20 rpm(Pa · s) 153 155 169 87 30 3.7  2rpm/20 rpm 6.4 6.4 6.2 6.6 5.0 1.7 After 7 Days  2 rpm(Pa · s) 990 10101010 554 260 8.4 20 rpm(Pa · s) 157 158 163 87 55 4.8  2 rpm/20 rpm 6.36.4 6.2 6.4 4.7 1.8 Rate of Viscosity Increase  2 rpm(%) 99 102 96 97173 135 20 rpm(%) 103 102 96 100 183 130

As can be clearly seen from Table 7, the polyvinyl chloride solsprepared using the surface-treated calcium carbonates of Examples 1–9 inaccordance with the present invention exhibit high viscosity levels andgood thixotropic properties. They also exhibit good storage stability.

(Viscosity Test of Acrylic Sol)

Each of the surface-treated calcium carbonates obtained in Examples 1–9and Comparative Examples 1–3 was formulated into an acrylic sol and itsviscosity was subsequently measured. 150 g of the surface-treatedcalcium carbonate, 300 g of an acrylic resin, 300 g of DINP, 100 g ofheavy calcium carbonate (product name “WHITON P-30”, product ofShiraishi Kogyo Co., Ltd.), 50 g of a diluent (product name “MINERALTURPEN”, product of Yamakei Sangyo Co., LTd.), 100 g of a tackifier(product name “BARSAMIDE 140”, product of Henkel Japan Ltd.) and 2.5 gof an isocyanate resin were fully mixed to prepare the acrylic sol. Aviscosity of the resulting acrylic sol both initially and after 7 dayswas measured in the same manner as described above. The measurementresults are shown in Table 8.

TABLE 8 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Immediately After Mixing  2rpm(Pa · s) 870 790 850 900 890 850 20 rpm(Pa · s) 143 132 144 145 148140  2 rpm/20 rpm 6.1 6.0 5.9 6.2 6.0 6.1 After 1 Day  2 rpm(Pa · s) 880830 860 910 900 870 20 rpm(Pa · s) 145 141 150 148 151 146  2 rpm/20 rpm6.1 5.9 5.7 6.2 6.0 6.0 Rate of Viscosity Increase  2 rpm(%) 101 105 101101 109 102 20 rpm(%) 101 107 104 102 110 104 Ex. 7 Ex. 8 Ex. 9 Comp.Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Immediately After Mixing  2 rpm(Pa · s)910 900 880 430 380 450 20 rpm(Pa · s) 143 144 146 87 93 103  2 rpm/20rpm 6.4 6.3 6.0 4.9 4.1 4.3 After 1 Day  2 rpm(Pa · s) 910 920 910 504450 510 20 rpm(Pa · s) 146 150 153 100 120 118  2 rpm/20 rpm 6.2 6.1 5.95.0 3.8 4.3 Rate of Viscosity Increase  2 rpm(%) 100 102 103 117 118 11320 rpm(%) 102 104 105 115 129 109

As can be clearly seen from Table 8, the acrylic sols prepared using thesurface-treated calcium carbonates of Examples 1–9 in accordance withthe present invention exhibit high viscosity levels and good thixotropicproperties. They also exhibit good storage stability.

UTILITY IN INDUSTRY

The surface-treated calcium carbonate of the present invention is amaterial for imparting thixotropy which, when loaded in a polymericmaterial such as an ink, paint, sealing medium, PVC sol or acrylic sol,can impart high viscosity and satisfactory thixotropic propertiesthereto. It shows little viscosity change with time and thus hassuperior storage stability.

Because the material for imparting thixotropy comprises calciumcarbonate, it can be produced at a relative low price and thus has aneconomical benefit.

The paste resin composition of the present invention can be formulatedinto a polyurethane sealant, modified silicone sealant, siliconesealant, polysulfide sealant, polyvinyl chloride sol, acrylic sol or thelike, and has high viscosity and satisfactory thixotropic properties.Also, it shows little viscosity change with time and thus has superiorstorage stability.

1. A material for imparting thixotropy comprising surface-treatedcalcium carbonate which results from surface treatment of calciumcarbonate having a BET specific surface area of 10–100 m²/g with anunsaturated fatty acid (A) and a saturated fatty acid (B), characterizedin that said material for imparting thixotropy exhibits a modal poresize peak at below 0.03 μm and a modal pore volume of 0.05–0.5 cm³/g ona pore size distribution curve derived from mercury porosimetry, and the(A)/(B) blending ratio of said unsaturated fatty acid (A) and saturatedfatty acid (B) is 0.5–1.9.
 2. The material for imparting thixotropy asrecited in claim 1, characterized in that said unsaturated fatty acid(A) and saturated fatty acid (B) are used in their metal salt or esterforms to effect the surface treatment.
 3. The material for impartingthixotropy as recited in claim 1, characterized in that said unsaturatedfatty acid (A) and saturated fatty acid (B) have a carbon number of6–31, respectively.
 4. A paste resin composition containingsurface-treated calcium carbonate which results from surface treatmentof calcium carbonate having a BET specific surface area of 10–100 m²/gwith an unsaturated fatty acid (A) and a saturated fatty acid (B),characterized in that said surface-treated calcium carbonate exhibits amodal pore size peak at below 0.03 μm and a modal pore volume of0.05–0.5 cm³/g on a pore size distribution curve derived from mercuryporosimetry, and the (A)/(B) blending ratio of said unsaturated fattyacid (A) and saturated fatty acid (B) is 0.5–1.9.
 5. A paste resincomposition as recited in claim 4, characterized in that saidunsaturated fatty acid (A) and saturated fatty acid (B) are used intheir metal salt or ester forms to effect the surface treatment.
 6. Apaste resin composition as recited in claim 4, characterized in thatsaid unsaturated fatty acid (A) and saturated fatty acid (B) have acarbon number of 6–31, respectively.
 7. The paste resin composition asrecited in claim 4, characterized as constituting a polyurethanesealant.
 8. The paste resin composition as recited in claim 4,characterized as constituting a modified silicone sealant.
 9. The pasteresin composition as recited in claim 4, characterized as constituting asilicone sealant.
 10. The paste resin composition as recited in claim 4,characterized as constituting a polysulfide sealant.
 11. The paste resincomposition as recited in claim 4, characterized as constituting apolyvinyl chloride sol.
 12. The paste resin composition as recited inclaim 4 characterized as constituting an acrylic sol.